4. Cell Fractionation

Question 1

what are the three main stages of cell fractionation?

Answer 1

1. Homogenisation
2. Filtration
3. Ultracentrifugation

Question 2

to homogenise a cell, it must be placed in a solution with which conditions?

Answer 2

• isotonic, prevent the cell from swelling/shrinking
• ice cold, to prevent enzymes digesting organelles
• buffer solution, maintain the same pH

Question 3

what is the role of cell fractionation?

Answer 3

to separate cellular components, whilst keeping their distinct functions

Question 4

describe the process of cell fractionation

Answer 4

1. Homogenisation: breaking up the cell, prepare the sample in a test tube and add the solution
2. Filtration: the homogenised cell is filtered through a gauze to remove remaining big structures
   3: Ultracentrifugation: the cell fragment are poured into a tube, tube is put into a centrifuge and spun slowly, separating the organelles, this process is repeated until all organelles are separated out

Question 5

what happens to the larger organelles during ultracentrifugation?

Answer 5

• they are flung to the bottom to form a pellet

Question 6

what happens to the smaller organelles during ultracentrifugation?

Answer 6

they stay suspended at the top, forming a supernatant